The elm leaf beetle was first discovered in Melbourne on the Mornington Peninsula in 1989 and quickly spread to the inner city suburb of East Melbourne. By 1994, the elm leaf beetle had established itself throughout the eastern suburbs, including the City of Whitehorse.
Council is responsible for 400 elms planted in reserves and as street trees. There are many more elms planted on private property, especially the popular Golden Elm.
Yellow and dark brown adult beetles are evident from mid-October and create a series of small holes in leaves during October and November.
Beetle larvae, also yellow and dark brown, then destroy all but the veins of leaves, creating a ‘skeleton’ effect.
The larvae descend the trunk during December and are visible on the ground below the tree. There may be up to three life cycles of the beetle in a single season, depending on the weather conditions.
Trees affected by elm leaf beetles can become defoliated by mid-summer, so there is no summer shade or autumn colours, and reduced energy reserves for next year’s growth.
Repeated infestations and defoliation seriously weaken trees. Total eradication of elm leaf beetle is extremely difficult. The main aim is to maintain elm leaf beetle numbers and damage to an acceptable level.
Council uses Arbor Spray Pty Ltd (mob: 0419 276 365) to control elm leaf beetles on Council-managed elm trees.
This company has a good knowledge of the elm leaf beetle life cycle and the licence needed to use control agents. Residents with elms on their private property are encouraged to control elm leaf beetles to limit future infestations.
Council uses the following methods to control elm leaf beetles on Council-owned trees:
The insecticide Confidor is injected around the root zone of the tree where it is taken up by the roots and translocated to the foliage. This is a safe and effective method of treating large trees. Based on experience overseas, the tree can be protected for more than one season. The best time for this treatment is September to November although later treatments are effective provided soil moisture is not limited.
Carbaryl banding is easy to do, uses small amounts of chemical and is effective in reducing the larval population of the elm leaf beetle. Carbaryl is a contact insecticide, widely used against many plant-eating pests. A 2% solution (20g active ingredient) is sprayed in a half-metre band around the trunk, at least 1.5m above the ground. Spraying needs to be done monthly when there are mature elm leaf beetle larvae, from around November through January. In wet weather conditions, the spray will need to be reapplied.
Council is a corporate member of Friends of the Elms Inc (FOTE). FOTE is a not-for-profit organisation, which was founded in 1990. The organisation exists to enable local government and government bodies to liaise with the public and keep people informed on the threats to elm trees and how they can assist in various ways.
The main medium for on-going communication is a quarterly newsletter Elm Watch, mailed to members of Friends of the Elms.
Council strongly advises the owners of elms in Whitehorse to become members of FOTE and register their elm trees on the state-wide Elm Register. FOTE can be contacted at the following address:
For further information, please phone Council on 9262 6222 and ask to speak to the ParksWide Department.
379-397 Whitehorse Road, Nunawading, Victoria 3131Australia
Tel: (03) 9262 6333 Fax: (03) 9262 6490Email: firstname.lastname@example.org